Conventional area denial technology has been applied, for example, in military settings to deny personnel and vehicles from passing across a particular surface area called a denial zone. Passage of a target into the denial zone is detected by object proximity technologies including trip wires, acoustic sensors, compression plate sensors, and laser beam occlusion sensors. Denial may be accomplished by lethal force such as used in antipersonnel land mines, antivehicle land mines, and projectiles intended to strike the target. In some systems, denial may be automatic upon detecting a disturbance in the denial zone.
Conventional area denial fails or is considered unsuccessful when a suitable target passes through the denial zone. Failure may be due to ineffective deployment of force to stop the intrusion or due to insensitivity. Force may be ineffective when deployed with insufficient accuracy. In addition, conventional area denial systems generally suffer from a high incidence of false alarms.
A false alarm is an event where force is deployed but no suitable target is available to effect meaningful denial. The target may not be a suitable target, for example, where an area denial system is planned against human intruders but responds inappropriately to animals, wind blown foliage, or changes in surface illumination. The target may be unavailable because it is not actually in the denial zone, or is in the zone but is out of range of denial forces (e.g., in a dead portion of the denial zone).
Insensitivity occurs when a suitable target is available in the denial zone without an appropriate response by the area denial system. Insensitivity may occur when the target goes undetected, is misclassified as an unsuitable target, or is erroneously determined to be unavailable (e.g., cannot be acquired by targeting technology).
Some conventional area denial systems provide notice to an operator before deploying force intended to stop a target. These systems are called man-in-the-loop systems. The operator may issue a command to abort automatic deployment of force, authorize deployment of force, or may muster other resources to respond to the threat indicated by the system. These systems are generally expensive because it is difficult to staff alert human operators. These systems are subject to failure to actually accomplish area denial for example due to operator insensitivity.
Conventional area denial systems include antipersonnel land mines that deploy nonlethal force such as electronic control devices as taught by U.S. Pat. No. 5,936,183 to McNulty. In such systems, automatic deployment follows disturbance detection. Notice is provided to system operators for mustering resources to respond to the breach of security that the area denial deployment implies to have occurred. In such systems, after detecting a disturbance, all nonlethal resources are deployed in a small set of directions into the denial zone. There remains a significant probability of unsuccessfully denying passage of a suitable target through the zone. Further, the force taught by McNulty is known to be insufficient to halt locomotion by a human or animal target. An apparatus for inhibiting locomotion of a target disclosed herein may be of the type sufficient to halt locomotion.
In nonmilitary settings, monitoring technologies have been used for data collection, and for providing increased safety or security for persons and property. These systems are capable of denying access (e.g., denying opening a door to a nonemployee) but are not capable of deploying force to deny movement through a denial zone.
Area denial technology and monitoring technology as discussed above include disturbance detection (e.g., sensor networks), surveillance (e.g., video signal detection, processing, transmission), target classification (e.g., video signal analysis), transmission of notice of an intrusion event (e.g., radio contact to dispatch soldiers, telephone contact to local police), and display of information (e.g., processed video from surveillance, notice to an operator). These technologies are not sufficient to meet significant demand for high safety and high security installations.
New applications for area denial cannot be met with conventional area denial technologies. For example, if conventional area denial technology was to be used in a prison, or near a utility substation having dangerous equipment, lethal force would be unwarranted; and mere notice of intrusion may be insufficient to accomplish the intended safety and/or security purposes. Conventional nonlethal area denial systems are inaccurate and subject to high incidence of false alarms and insensitivity. Without the present invention, area denial systems cannot meet user requirements for a high level of safety and/or security.